This invention relates to a carding machine for processing textile fibers and is more particularly concerned with a cylinder screen having a frame which has two parallel lateral components and a screening surface provided with a great number of apertures.
In a cylinder screen of the above-outlined type, the closed (aperture-free) zone of the screen structure oriented towards the doffer has at its outer end an enlarged rim (hereafter bead or beaded rim) having a radius of, for example, 5-15 mm. The bead is to facilitate, by virtue of its curved shape, the transfer and arrangement of the textile fibers from the cylinder to the doffer. The closed zone of the cylinder screen and the bead project into the space between the cylinder and the doffer. The air entrained by the cylinder forms an air cushion between the bead and the bight defined by the cylinder and the doffer, so that the transfer of the textile fibers from the cylinder to the doffer occurs in the vicinity of the bight. Since in the zone of the air cushion there is practically no air flow, the textile fibers which arrive in this zone, settle on the surface of the bead and are not carried away by the cylinder clothing. As additional fibers adhere to the first-settled individual fibers, a "fiber carpet" is formed which may, to a substantial extent, adversely affect the proper operation of the card. It is a further disadvantage that the compressed air introduced into the narrow gap between the cylinder clothing and the screen, is driven out laterally from the screen into the surrounding space.